Sonochemical deposition of nanosized Au on titanium oxides with different surface coverage and their photocatalytic activity

Different surface coverage of nanosized Au on the TiO2 matrix was simply fabricated in an ultrasound-driven cell by adjusting the loading volume of gold precursor. Non-annealed Au–TiO2 composites with low surface coverage of nanosized Au exhibited a significantly enhanced photocatalytic activity in comparison to pristine TiO2. However, a further increase of nanosized Au loading consequently led to a decrease of photocatalytic efficiency of Au-deposited TiO2, probably due to the reduction of available surface area for organic pollutant adsorption and light absorption. The X-ray photoelectron spectroscopy (XPS) analysis of Au-deposited TiO2 indicated the coexistence of metallic Auo and non-metallic Au species that might play a role as an electron scavenger. The reduction of photoluminescence (PL) intensity also indicated the efficient separation of electrons and holes even in Au–TiO2 composites without heat treatment.